Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
4. Compositions of Isometries
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Exercise 43 Page 576

C

Practice makes perfect
We have been given the side lengths of a triangle. 7 in. 9 in. We can find the range of possible lengths for the third side of the triangle, x inches, using the Triangle Inequality Theorem. This theorem states that the sum of the lengths of any two sides of a triangle is greater than the length of the third side. Let's remember the theorem.

XY+YZ> XZ YZ+ XZ> XY XZ+ XY>YZ Applying this theorem to the given side lengths, we have three inequalities. I:& 7+9> x ⇒ 16 > x II:&9+ x> 7 ⇒ x > -2 III:& x+ 7>9 ⇒ x > 2 The range for the possible lengths of the third side can be found by looking at the overlapping regions for these inequalities.

In interval notation, this can be written as a compound inequality. 2 in.< x< 16 in. Our answer corresponds to option C.